[PATCH 08/35] cifs: Improve SMB2+ stat() to work also for paths in DELETE_PENDING state

["Pali Rohár" <pali@kernel.org>]

Paths in DELETE_PENDING state cannot be opened at all. So standard way of
querying path attributes for this case is not possible.

There is an alternative way how to query limited information about file
over SMB2+ dialects without opening file itself. It is by opening the
parent directory, querying specific child with filled search filter and
asking for attributes for that child.

Implement this fallback when standard case in smb2_query_path_info fails
with STATUS_DELETE_PENDING error and stat was asked for path which is not
top level one (because top level does not have parent directory at all).

Depends on "cifs: Change translation of STATUS_DELETE_PENDING to -EBUSY".

Signed-off-by: Pali Rohár <pali@kernel.org>
---
 fs/smb/client/cifsglob.h  |   1 +
 fs/smb/client/smb2glob.h  |   1 +
 fs/smb/client/smb2inode.c | 177 +++++++++++++++++++++++++++++++++++++-
 3 files changed, 176 insertions(+), 3 deletions(-)

diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
index e6830ab3a546..0ecf4988664e 100644
--- a/fs/smb/client/cifsglob.h
+++ b/fs/smb/client/cifsglob.h
@@ -2337,6 +2337,7 @@ struct smb2_compound_vars {
 	struct smb_rqst rqst[MAX_COMPOUND];
 	struct kvec open_iov[SMB2_CREATE_IOV_SIZE];
 	struct kvec qi_iov;
+	struct kvec qd_iov[SMB2_QUERY_DIRECTORY_IOV_SIZE];
 	struct kvec io_iov[SMB2_IOCTL_IOV_SIZE];
 	struct kvec si_iov[SMB2_SET_INFO_IOV_SIZE];
 	struct kvec close_iov;
diff --git a/fs/smb/client/smb2glob.h b/fs/smb/client/smb2glob.h
index 224495322a05..1cb219605e75 100644
--- a/fs/smb/client/smb2glob.h
+++ b/fs/smb/client/smb2glob.h
@@ -39,6 +39,7 @@ enum smb2_compound_ops {
 	SMB2_OP_GET_REPARSE,
 	SMB2_OP_QUERY_WSL_EA,
 	SMB2_OP_OPEN_QUERY,
+	SMB2_OP_QUERY_DIRECTORY,
 };
 
 /* Used when constructing chained read requests. */
diff --git a/fs/smb/client/smb2inode.c b/fs/smb/client/smb2inode.c
index 2a0316c514e4..460e75614ef1 100644
--- a/fs/smb/client/smb2inode.c
+++ b/fs/smb/client/smb2inode.c
@@ -176,6 +176,9 @@ static int smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 			    struct kvec *out_iov, int *out_buftype, struct dentry *dentry)
 {
 
+	bool has_cifs_mount_server_inum = cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM;
+	struct smb2_query_directory_req *qd_rqst = NULL;
+	struct smb2_query_directory_rsp *qd_rsp = NULL;
 	struct smb2_create_rsp *create_rsp = NULL;
 	struct smb2_query_info_rsp *qi_rsp = NULL;
 	struct smb2_compound_vars *vars = NULL;
@@ -344,6 +347,41 @@ static int smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 			trace_smb3_posix_query_info_compound_enter(xid, tcon->tid,
 								   ses->Suid, full_path);
 			break;
+		case SMB2_OP_QUERY_DIRECTORY:
+			rqst[num_rqst].rq_iov = &vars->qd_iov[0];
+			rqst[num_rqst].rq_nvec = SMB2_QUERY_DIRECTORY_IOV_SIZE;
+
+			rc = SMB2_query_directory_init(xid,
+						       tcon,
+						       server,
+						       &rqst[num_rqst],
+						       cfile ?
+							cfile->fid.persistent_fid : COMPOUND_FID,
+						       cfile ?
+							cfile->fid.volatile_fid : COMPOUND_FID,
+						       0,
+						       has_cifs_mount_server_inum ?
+							SMB_FIND_FILE_ID_FULL_DIR_INFO :
+							SMB_FIND_FILE_FULL_DIRECTORY_INFO);
+			if (!rc) {
+				/*
+				 * Change the default search wildcard pattern '*'
+				 * to the requested file name stored in in_iov[i]
+				 * and request for only one single entry.
+				 */
+				qd_rqst = rqst[num_rqst].rq_iov[0].iov_base;
+				qd_rqst->Flags |= SMB2_RETURN_SINGLE_ENTRY;
+				qd_rqst->FileNameLength = cpu_to_le16(in_iov[i].iov_len);
+				rqst[num_rqst].rq_iov[1] = in_iov[i];
+			}
+			if (!rc && (!cfile || num_rqst > 1)) {
+				smb2_set_next_command(tcon, &rqst[num_rqst]);
+				smb2_set_related(&rqst[num_rqst]);
+			} else if (rc) {
+				goto finished;
+			}
+			num_rqst++;
+			break;
 		case SMB2_OP_DELETE:
 			trace_smb3_delete_enter(xid, tcon->tid, ses->Suid, full_path);
 			break;
@@ -730,6 +768,64 @@ static int smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 				trace_smb3_posix_query_info_compound_done(xid, tcon->tid,
 									  ses->Suid);
 			break;
+		case SMB2_OP_QUERY_DIRECTORY:
+			if (rc == 0) {
+				qd_rsp = (struct smb2_query_directory_rsp *)
+					rsp_iov[i + 1].iov_base;
+				rc = smb2_validate_iov(le16_to_cpu(qd_rsp->OutputBufferOffset),
+						       le32_to_cpu(qd_rsp->OutputBufferLength),
+						       &rsp_iov[i + 1],
+						       has_cifs_mount_server_inum ?
+							sizeof(SEARCH_ID_FULL_DIR_INFO) :
+							sizeof(FILE_FULL_DIRECTORY_INFO));
+			}
+			if (rc == 0) {
+				/*
+				 * Both SEARCH_ID_FULL_DIR_INFO and FILE_FULL_DIRECTORY_INFO
+				 * have same member offsets except the UniqueId and FileName.
+				 */
+				SEARCH_ID_FULL_DIR_INFO *si =
+					(SEARCH_ID_FULL_DIR_INFO *)qd_rsp->Buffer;
+
+				idata = in_iov[i + 1].iov_base;
+				idata->fi.CreationTime = si->CreationTime;
+				idata->fi.LastAccessTime = si->LastAccessTime;
+				idata->fi.LastWriteTime = si->LastWriteTime;
+				idata->fi.ChangeTime = si->ChangeTime;
+				idata->fi.Attributes = si->ExtFileAttributes;
+				idata->fi.AllocationSize = si->AllocationSize;
+				idata->fi.EndOfFile = si->EndOfFile;
+				idata->fi.EASize = si->EaSize;
+				idata->fi.Directory =
+					!!(le32_to_cpu(si->ExtFileAttributes) & ATTR_DIRECTORY);
+				/*
+				 * UniqueId is present only in struct SEARCH_ID_FULL_DIR_INFO.
+				 * It is not present in struct FILE_FULL_DIRECTORY_INFO.
+				 * struct SEARCH_ID_FULL_DIR_INFO was requested only when
+				 * CIFS_MOUNT_SERVER_INUM is set.
+				 */
+				if (has_cifs_mount_server_inum)
+					idata->fi.IndexNumber = si->UniqueId;
+				/*
+				 * Do not change idata->fi.NumberOfLinks to correctly
+				 * trigger the CIFS_FATTR_UNKNOWN_NLINK flag.
+				 */
+				/*
+				 * Do not change idata->fi.DeletePending as we do not know if
+				 * the entry is in the delete pending state. SMB2 QUERY_DIRECTORY
+				 * at any level does not provide this information.
+				 */
+			}
+			SMB2_query_directory_free(&rqst[num_rqst++]);
+			if (rc)
+				trace_smb3_query_dir_err(xid,
+					cfile ? cfile->fid.persistent_fid : COMPOUND_FID,
+					tcon->tid, ses->Suid, 0, 0, rc);
+			else
+				trace_smb3_query_dir_done(xid,
+					cfile ? cfile->fid.persistent_fid : COMPOUND_FID,
+					tcon->tid, ses->Suid, 0, 0);
+			break;
 		case SMB2_OP_DELETE:
 			if (rc)
 				trace_smb3_delete_err(xid, tcon->tid, ses->Suid, rc);
@@ -1090,9 +1186,9 @@ int smb2_query_path_info(const unsigned int xid,
 		break;
 	case -EREMOTE:
 		break;
-	default:
-		if (hdr->Status != STATUS_OBJECT_NAME_INVALID)
-			break;
+	}
+
+	if (hdr->Status == STATUS_OBJECT_NAME_INVALID) {
 		rc2 = cifs_inval_name_dfs_link_error(xid, tcon, cifs_sb,
 						     full_path, &islink);
 		if (rc2) {
@@ -1101,6 +1197,81 @@ int smb2_query_path_info(const unsigned int xid,
 		}
 		if (islink)
 			rc = -EREMOTE;
+	} else if (hdr->Status == STATUS_DELETE_PENDING && full_path[0]) {
+		/*
+		 * If SMB2 OPEN/CREATE fails with STATUS_DELETE_PENDING error,
+		 * it means that the path is in delete pending state and it is
+		 * not possible to open it until some other client clears delete
+		 * pending state or all other clients close all opened handles
+		 * to that path.
+		 *
+		 * There is an alternative way how to query limited information
+		 * about path which is in delete pending state still suitable
+		 * for the stat() syscall. It is by opening the parent directory,
+		 * querying specific child with filled search filer and asking
+		 * for attributes for that child.
+		 */
+
+		char *parent_path;
+		const char *basename;
+		__le16 *basename_utf16;
+		int basename_utf16_len;
+		struct cifsFileInfo *parent_cfile;
+
+		basename = strrchr(full_path, CIFS_DIR_SEP(cifs_sb));
+		if (basename) {
+			parent_path = kstrndup(full_path, basename - full_path, GFP_KERNEL);
+			basename++;
+		} else {
+			parent_path = kstrdup("", GFP_KERNEL);
+			basename = full_path;
+		}
+
+		if (!parent_path) {
+			rc = -ENOMEM;
+			goto out;
+		}
+
+		basename_utf16 = cifs_convert_path_to_utf16(basename, cifs_sb);
+		if (!basename_utf16) {
+			kfree(parent_path);
+			rc = -ENOMEM;
+			goto out;
+		}
+
+		basename_utf16_len = 2 * UniStrnlen((wchar_t *)basename_utf16, PATH_MAX);
+
+retry_query_directory:
+		num_cmds = 1;
+		cmds[0] = SMB2_OP_QUERY_DIRECTORY;
+		in_iov[0].iov_base = basename_utf16;
+		in_iov[0].iov_len = basename_utf16_len;
+		in_iov[1].iov_base = data;
+		in_iov[1].iov_len = sizeof(*data);
+		oparms = CIFS_OPARMS(cifs_sb, tcon, parent_path, FILE_READ_DATA,
+				     FILE_OPEN, CREATE_NOT_FILE, ACL_NO_MODE);
+		cifs_get_readable_path(tcon, parent_path, &parent_cfile);
+		free_rsp_iov(out_iov, out_buftype, ARRAY_SIZE(out_iov));
+		rc = smb2_compound_op(xid, tcon, cifs_sb, parent_path,
+				      &oparms, in_iov, cmds, num_cmds,
+				      parent_cfile, out_iov, out_buftype, NULL);
+		if (rc == -EOPNOTSUPP && (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM)) {
+			/*
+			 * If querying of server inode numbers is not supported
+			 * but is enabled, then disable it and try again.
+			 */
+			cifs_autodisable_serverino(cifs_sb);
+			goto retry_query_directory;
+		}
+
+		kfree(parent_path);
+		kfree(basename_utf16);
+
+		hdr = out_iov[0].iov_base;
+		if (!hdr || out_buftype[0] == CIFS_NO_BUFFER)
+			goto out;
+
+		data->fi.DeletePending = 1; /* This is code path for STATUS_DELETE_PENDING. */
 	}
 
 out:
-- 
2.20.1